I remember being here in 2017 also and I definitely recall the quality of the post being much higher. Even looking at the sidebar, most of the high quality AMAs from prominent researchers where prior to 2018. Now I often see posts that I would classify as relevant, correct or high quality get downvoted, and posts that seem misinformed or incorrect get upvoted. Personally I blame the reddit redesign for deemphasizing text and discussion in favor of lowest common denominator stuff like eye catching images and video.